From: Tom Lane <tgl@sss.pgh.pa.us>
To: plsqlvids01 plsqlvids01 <plsqlvids01@gmail.com>
cc: pgsql-general@lists.postgresql.org
Subject: Re: use of postgres reg* datatypes in user tables?
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Comments: In-reply-to plsqlvids01 plsqlvids01 <plsqlvids01@gmail.com>
	message dated "Mon, 19 Aug 2024 02:08:48 -0400"
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Date: Mon, 19 Aug 2024 08:50:51 -0400
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plsqlvids01 plsqlvids01 <plsqlvids01@gmail.com> writes:
> What is the use of postgres regclass datatype in user tables? When would
> one want to use them when regular data types are available? If any tables
> have these data types, since pg_upgrade would fail, what data types should
> those be converted to?

Indeed, storing reg* types in user tables isn't particularly
recommended because of the pg_upgrade problem.  However, casting
to a reg* type is plenty useful in queries on the system catalogs.
There is more info and examples in the manual:

https://www.postgresql.org/docs/current/datatype-oid.html

			regards, tom lane